Digestibility of energy, lipids and fatty acids of vegetable oils and poultry fat by pacuPiaractus mesopotamicus(Holmberg 1887)

Abstract

Evaluation of vegetable oils and poultry fat digestibility is the first step to elicit their use in aquafeeds. This work aimed at determining apparent digestibility coefficients (ADCs) of energy, lipids and fatty acids of oil sources for pacu, a widely farmed neotropical Characin. A semipurified, omnivorous fish diet (344.2 g kg−1 crude protein; 18.16 MJ kg−1 gross energy) was used as reference diet. Test diets were obtained by adding 2 g kg−1 chromium III oxide and replacing 15 g kg−1 reference diet with fish, soybean, colza, corn and flaxseed oils and poultry fat. Juvenile pacu (64 ± 10.8 g; 14.6 ± 1.1 cm) were fed to apparent satiety, four times a day, and then transferred to cylindrical–conical aquaria for collection of faeces by sedimentation (n = 3). Apparent digestibility coefficients of energy and lipids were high for all tested oils (P > 0.05); ADCs of saturated fatty acid (SFA) were lower than monounsaturated fatty acids (MUFA) and polyunsaturated fatty acid (PUFA). Essential fatty acids (18:2n-6 and 18:3n-3) had high ADC (>93%), colza oil and poultry fat yielding the lowest ADC for 18:2n-6 (P = 0.01) and 18:3n-3 (P < 0.01), respectively. Corn oil, soybean oil and flaxseed oil were interesting sources of 18:2n-6 and 18:3n-3 dietary fatty acids for pacu.